Southwestern Deserts

August, 2004
Regional Report

Monitor Water Needs

Hot summer temperatures and blowing winds dry out plants quickly. Water should soak 1 foot deep for small plants, 2 feet deep for shrubs, and 3 feet deep for trees. Watch for signs of water stress such as wrinkling, yellowing, browning, and wilting. Make sure drip emitters and sprinklers are not clogged.

Plan Ahead To Avoid Citrus Fruit Split

Splitting rinds show up now, most likely due to insufficient watering earlier in the growing season. This creates tough rinds that don\'t expand as the fruit increases in size. There\'s nothing to do about it now. Make a note on your calender for next year to water deeply through the tree\'s entire root zone (3 feet deep). Apply water where the feeder roots are located, at the edges of the tree\'s canopy.

Treat Plants With Yellowing Leaves

Non-native plants often show signs of iron chlorosis in late summer, evident when the leaves turn yellow with green veins. Iron chlorosis may occur from overwatering in combination with summer monsoons. Overly wet soil forces out oxygen. Roots must have oxygen to absorb iron. If chlorotic symptoms appear and you are not overwatering, apply iron chelates or ferrous sulfate, which roots readily absorb. Native plants seldom, if ever, have chlorosis problems.

Plant Palms

Summertime heat is the best time to transplant palm trees. Their roots thrive in these conditions. Decide how much space there is for the palm to grow, both vertically and horizontally. Choose a variety whose mature size will fit that space, as constant pruning and cutting back is unsightly and detrimental to the plant's long-term health. Keep root systems consistently moist until temperatures cool.

Sow Summer Squash

Pattypan, crookneck, and zucchini will still germinate in warm soil and produce a crop in the low desert or middle desert, depending on frost dates. Most varieties are relatively fast maturing -- 48 to 52 days. Sow seeds in a rich organic soil and keep them consistently moist until germination. After seedlings sprout, apply mulch to conserve moisture and reduce soil temperature.